This invention relates to a direct cylinder injected internal combustion engine and more particularly to an improved arrangement for cooling the fuel injector of such an engine.
In conjunction with the design of internal combustion engines, there is a continuing quest for improved fuel efficiency and better exhaust emission control. Various systems and techniques have been employed to achieve these purposes. One way in which it has been found that the combustion efficiency and emission control can be improved is by use of fuel injection. Fuel injectors permit cycle to cycle control and are generally more accurate than carburetors.
In addition, it is desirable to achieve some stratification in the fuel air mixture in the combustion chamber in order to permit leaner burning. That is, if the entire cylinder is filed with a stoichiometric mixture, under most running conditions, too much fuel is supplied for the required engine performance. Thus, if it is possible to achieve a stratified patch of stoichiometric mixture that is present at the gap of the spark plug at the time of firing, the entire cylinder need not be filled with a stoichiometric mixture and considerable improvements in fuel efficiency and exhaust emission control can resolve.
However, it generally is a fact that stratification can be achieved in an open chambered engine more easily if the fuel is injected directly into the combustion chamber. This will permit the achievement of stratification when desired and also will permit the filling of the cylinder with adequate fuel to obtain maximum power output. Thus, running throughout the entire speed and load ranges can be significantly improved. However, there is a significant problem in the positioning of the fuel injector in the cylinder head so as to achieve direct injection.
Not the least among these problems is the actual positioning of the injector in cylinder head. If high performance is sought and the engine utilizes multiple valves and overhead camshafts, the space availability for the fuel injector becomes limited. Also, it is desirable to position the spark plug generally at the center of the combustion chamber volume at top dead center so as to insure good flame propagation and complete combustion. This further adds to the difficulty in the positioning of the fuel injector.
Furthermore, there is the added difficulty of providing adequate cooling for the fuel injector. This is particularly true where the injector is side mounted and a centrally positioned spark plug is employed. Such side mounting arrangements preferably position the fuel injector on the intake side of the engine and below the induction passage. In this way, the heat from the exhaust gases are not likely to propagate to the fuel injector and deteriorate its performance.
However, this side placement and below the intake passages means that the fuel injector in conventional engines is not adequately cool. Cooling is still necessary because if the injector becomes heated, its efficiency can deteriorate. The problem is particularly true in connection with solenoid operated fuel injectors because the solenoid for actuating the injector valve consumes a fairly large amount of electrical energy and thus, generates a fairly large amount of heat.
It is, therefore, a principal object of this invention to provide an improved cylinder head and injector cooling arrangement for an internal combustion engine.
It is a further object of this invention to provide an improved fuel injector mounting arrangement for an overhead valve multiple valve engine wherein the injector is adequately cooled and nevertheless has the desired spray path.
It is a further object of this invention to provide an improved cylinder head and cooling jacket arrangement for a direct injected internal combustion engine.